Update screenshots

git-svn-id: https://plugins.svn.wordpress.org/add-to-any/trunk@773079 b8457f37-d9ea-0310-8a92-e5e31aec5664
Move screenshots to assets directory

git-svn-id: https://plugins.svn.wordpress.org/add-to-any/trunk@773080 b8457f37-d9ea-0310-8a92-e5e31aec5664